Aspirin and heparin for the prevention of pre-eclampsia: protocol for a systematic review and network meta-analysis

Introduction Pre-eclampsia is an important cause of death and complication for pregnant women and perinatal infant. Low-dose aspirin has been most commonly used to prevent pre-eclampsia in high-risk pregnant women. Recently, heparins have also been used alone or in combination with aspirin to prevent pre-eclampsia. However, the optimal doses and combination therapy of aspirin and heparins are not well established. Therefore, we aim to compare aspirin, heparins and their combination to prevent pre-eclampsia in a network meta-analysis. Methods and analysis We will search the following electronic databases from the date of database establishment to 8 January 2019: PubMed, Embase, Cochrane Library, Web of Science and ProQuest. We will also search additional studies manually. There will be no restriction on the language of publications. Only randomised clinical trials will be eligible in our network meta-analysis. We will include pregnant women who have been recommended for aspirin according to the standard of the American Congress of Obstetricians and Gynecologists, or were designated as high risk in some recent studies. We will include studies comparing the effects of any single or combination of aspirin and heparins with placebo or observation or another intervention in pregnancy. We will include studies that reported one of the following outcomes: pre-eclampsia, severe pre-eclampsia, preterm delivery, perinatal death and full-term pre-eclampsia with delivery at >= 37 weeks. Traditional pairwise meta-analysis will be performed initially, and then network meta-analysis will be performed using frequency analysis method. Subgroup analyses and sensitivity analyses will be conducted to assess the robustness of the findings. Ethics and dissemination This network meta-analysis does not require ethical certification. An overview and information on the prevention of pre-eclampsia in high-risk pregnant women will be provided by this network metaanalysis.